A joining technique and design for welding hard to weld elements of a disk drive suspension machines or coins the parts to be welded at their weld interface. A small pocket is formed at the weld interface to let evaporated material gases escape during welding and reduce gas bubble trapping in the weld nugget. For laser welding, a pocket is formed in thick parts to control the welded web thickness for fast melting and thorough mixing of top and bottom materials. For resistance spot welding, it may be necessary to form pockets in both materials on the electrode contact side to reduce material thickness. This technique provides a weld interface design that solves joint reliability and dynamic variation problems. This technique can be used to attach aluminum-to-aluminum or other materials that are difficult to weld due to porous welds, and to improve weld quality of both spot and seam welds.
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1. A method of joining materials, comprising:
providing a first component with a gas release pocket in a first surface that extends from an interior portion of the first component to an exterior of the first component; positioning a second component adjacent to the first component such that the gas release pocket is located therebetween and is in communication with an atmosphere; supplying an inert gas to reduce oxidation of the weld; welding the first component to the second component by applying local heat to a weld site on one of the components to form a weld nugget that extends through the gas release pocket and between the first and second components; and releasing weld-related gases to the atmosphere through the gas release pocket to reduce a porosity of the weld nugget.
13. A method of joining materials, comprising:
providing a first component with a gas release pocket in a first surface that extends from an interior portion of the first component to an exterior of the first component; positioning a second component adjacent to the first component such that the gas release pocket is located therebetween and is in communication with an atmosphere; welding the first component to the second component by applying local heat to a weld site on one of the components to form a weld nugget that extends through the gas release pocket and between the first and second components; providing a formed shape of welding rod material at the weld site to form a stronger homogenous weld nugget; and releasing weld-related gases to the atmosphere through the gas release pocket to reduce a porosity of the weld nugget.
8. A method of joining materials, comprising:
providing a first component with a gas release pocket in a first surface that extends from an interior portion of the first component to an exterior of the first component; positioning a second component adjacent to the first component such that the gas release pocket is located therebetween and is in communication with an atmosphere; welding the first component to the second component by applying local heat to a weld site on one of the components to form a weld nugget that extends through the gas release pocket and between the first and second components; forming a weld pocket at said weld site in order to reduce a welded web thickness and reduce the input heat energy required to complete the weld; and releasing weld-related gases to the atmosphere through the gas release pocket to reduce a porosity of the weld nugget.
2. The method of
3. The method of
4. The method of
5. The method of
6. The method of
7. The method of
shearing off the first component to form a sheared weld nugget having protrusions extending from the second component; locating a replacement first component on the second component such that a replacement gas release pocket on the replacement first component accommodates the protrusions; welding the replacement first component to the second component by applying local heat to a replacement weld site on one of the replacement first component and the second component to melt the sheared weld nugget and form a replacement weld nugget that extends through the replacement gas release pocket and between the first and second components, and excess material of the sheared weld nugget, now as part of the replacement weld nugget, grows into the replacement gas release pocket; and releasing weld-related gases to the atmosphere through the replacement gas release pocket to reduce a porosity of the replacement weld nugget.
9. The method of
10. The method of
11. The method of
12. The method of
shearing off the first component to form a sheared weld nugget having protrusions extending from the second component; locating a replacement first component on the second component such that a replacement gas release pocket on the replacement first component accommodates the protrusions; welding the replacement first component to the second component by applying local heat to a replacement weld site on one of the replacement first component and the second component to melt the sheered weld nugget and form a replacement weld nugget that extends through the replacement gas release pocket and between the first and second components, and excess material of the sheared weld nugget, now as part of the replacement weld nugget, grows into the replacement gas release pocket; and releasing weld-related gases to the atmosphere through the replacement gas release pocket to reduce a porosity of the replacement weld nugget.
14. The method of
15. The method of
16. The method of
17. The method of
shearing off the first component to form a sheared weld nugget having protrusions extending from the second component; locating a replacement first component on the second component such that a replacement gas release pocket on the replacement first component accommodates the protrusions; welding the replacement first component to the second component by applying local heat to a replacement weld site on one of the replacement first component and the second component to melt the sheared weld nugget and form a replacement weld nugget that extends through the replacement gas release pocket and between the first and second components, and excess material of the sheared weld nugget, now as part of the replacement weld nugget, grows into the replacement gas release pocket; and releasing weld-related gases to the atmosphere through the replacement gas release pocket to reduce a porosity of the replacement weld nugget.
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1. Technical Field
The present invention relates in general to an improved welding technique, and in particular to an improved part interface design and method for laser spot welding materials that are difficult to weld together.
2. Description of the Prior Art
Generally, a data access and storage system consists of one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. The hard disks themselves are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, one to six disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
A typical HDD also utilizes an actuator assembly. The actuator moves magnetic read/write heads to the desired location on the rotating disk so as to write information to or read data from that location. Within most HDDs, the magnetic read/write head is mounted on a slider. A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirably contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions on its air bearing surface (ABS) that enables the slider to fly at a constant height close to the disk during operation of the disk drive. A slider is associated with each side of each platter and flies just over the platter's surface. Each slider is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid actuator arm that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single movable unit having either a linear bearing or a rotary pivotal bearing system.
The head and arm assembly (HSA) is linearly or pivotally moved utilizing a magnet/coil structure that is often called a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which the spindle is also mounted. The base casting with its spindle, actuator VCM, and internal filtration system is then enclosed with a cover and seal assembly to ensure that no contaminants can enter and adversely affect the reliability of the slider flying over the disk. When current is fed to the motor, the VCM develops force or torque that is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head approaches a desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop and settle directly over the desired track.
Conventional disk drive components are formed primarily from aluminum and stainless steel materials. Stainless steel components such as suspension flexures, load beams, and mount plates are welded together. In contrast, aluminum components such as combs, covers, and base castings are bolted together due to the difficulty of welding aluminum to aluminum. Bolted joints are expensive, create contamination, and can creep under vibration and temperature variations, and have dynamic variations. Drive components are made of aluminum due to its low cost, good machining and formability, excellent heat transfer, and high stiffness-to-weight ratio. Also, stainless steel to stainless steel welds of suspension components result in localized distorsions that change the flatness of suspension components resulting in higher gain of some dynamic modes. In addition, future disk drives may need to be filled with gases like helium or may need internal pressures that are lower than atmospheric pressure. This will require sealing of the drive from the atmosphere that will need aluminum-to-aluminum seam welding of the drive cover to the base.
As stated above, some disk drive components are normally made of 6061 T6 aluminum or equivalent aluminum alloys. These alloys contain manganese, magnesium, etc., low melting point alloys. Components formed from these low melting point alloys evaporate as the aluminum melts during the welding process. Welding-generated gases are trapped in the welds and contribute to porosity and interfere with homogenous mixing of the molten bodies that form the weld nugget. Typically, porosity due to trapped weld gases is at a maximum and more harmful at the center of the weld interface. For high weld strength, the interface should be free of gas bubbles/porosity. Thus, an improved joining technique and design for disk drive components that overcomes the limitations of the prior art is needed.
One embodiment of a joining technique and design for welding of hard to weld elements of a disk drive suspension is disclosed. One or both parts to be welded are machined, coined, or etched at the weld interface. A small pocket, approximately 10 to 200 μm in depth, is formed in one or both of the parts at weld interface to communicate with the atmosphere to let evaporated material gases escape all around the weld during welding so as to greatly reduce gas bubble trapping in the weld nugget. The pocket also helps in reworkability of the joint by accommodating the sheared weld nugget protruding a small amount above the material surface at interface. The presence of bubbles or a porous consistency reduces the weld strength. For laser welding, if the top part is thick, a depression or pocket is formed therein to control the welded web thickness for fast melting and thorough mixing of top and bottom materials in order to form a strong reliable weld. For resistance spot welding, if both top and bottom materials are thick, it may be necessary to form these pockets in both materials on the electrode contact side to reduce material thickness. The technique utilized in the present invention provides a weld interface design that solves the joint reliability and dynamic variation problems. This technique can be used to attach aluminum-to-aluminum or other materials that are difficult to weld due to porous welds, and to improve weld quality of both spot and seam welds. Typical disk drive applications include elimination of fasteners to join aluminum parts together.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.
So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and therefore are not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.
Referring to
In the embodiment shown, each arm 125 has extending from it at least one cantilevered load beams or suspensions 127, a magnetic read/write transducer or head 129 mounted on a slider secured to a flexure that is flexibly mounted to each suspension 127. The read/write heads 129 magnetically read data from and/or magnetically write data to disks 115. The level of integration called head gimbal assembly is head 129 and the slider are mounted on suspension 127. The slider is usually bonded to the end of suspension 127. Head 129 is typically pico size (approximately 1250×1000×300 microns) and formed from ceramic or intermetallic materials. Head 129 also may be nano size (approximately 2050×1600×450 microns) and is pre-loaded against the surface of disk 115 (in the range two to ten grams) by suspension 127.
Suspensions 127 have a spring-like quality which biases or urges the slider air bearing surface against the disk to enable the creation of the air bearing film between the slider and disk surface. A voice coil 133 housed within a conventional voice coil motor magnet assembly 134 (top pole not shown) is also mounted to arms 125 opposite the head gimbal assemblies. Movement of the actuator 121 (indicated by arrow 135) by controller 119 moves head gimbal assemblies 129 radially across tracks on the disks 115 until the heads 129 settle on the target tracks. The head gimbal assemblies operate in a conventional manner and always move in unison with one another, unless drive 111 uses multiple independent actuators (not shown) wherein the arms can move independently of one another.
Referring now to
The opposite surface of arm 125 (
In operation (FIGS. 4 and 5), arm 125 is joined to comb 122, preferably with a laser welding technique. Comb 122 has at least one platform 147 to which each arm 125 is welded. Each platform 147 is generally flat and rectangular, and protrudes a short distance from the main body of comb 122. In the simplified version shown, comb 122 has three platforms 147, each of which can support two arms 125. As shown in
Arm 125 and platform 147 are shown prior to welding in
This design is especially beneficial for use with materials that are difficult to weld together, such as aluminum components. Although, it also helps in improving weld quality of all types of material by reducing porosity and distortion at and near the weld sites. If the two materials being welded are incompatible, an optional welding rod material formed pallet 146 may be used to help form weld nugget 153. Pallet 146 may be formed from, for example, 4047 aluminum or other materials and can be placed at the top (as shown) where laser beam strikes or in the pocket at weld interface (not shown).
In order for the remaining arms 125 (i.e., those other than the outermost arm) to be welded to their respective platform 147, the ability to offset laser welding beam 149 by a desired angle from perpendicular is even more critical. Because of the very limited distance between arms 125, the presence of weld pockets 143 (which reduce the thickness of the arm) ensure that an adequate weld nugget 153 is formed at each weld site. This element is particularly helpful for welding arms 125 having a greater thickness that would otherwise preclude the formation of an adequate weld nugget 153. After a weld has been formed in each of the weld pockets 143 of all of the upward-facing arms 125 (three shown), the comb stack or assembly (
Ideally, the arms 125 are formed from 4047 or other welding rod aluminum for better welds and reworkability, but the comb 122 can be formed from almost any other aluminum. If the arms 125 are formed from a material other than 4047 aluminum, 4047 aluminum may need to be used as a filler material to ensure that the arm material mixes with the material of the other component. In addition, the completed comb assembly (
Another embodiment of the present invention is depicted in
The present invention has several advantages including the ability to allow materials that are difficult to weld, such as aluminum, to be joined together via laser spot welding. The designed weld web thickness of the parts allow adequate laser weld nuggets to form, and the presence of the gas release pockets, which are connected to the atmosphere between the welded parts, prevent gas bubbles from being trapped in the weld nuggets in order to reduce their porosity. Comparing
While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.
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